Birdwatching (birding) is a nature-based recreational activity, often including arising early in the morning. In the present study, we tested the effect of a negative social jetlag (SJL) in birders. Negative SJL implies that people have an even earlier sleep-wake rhythm on free days or weekends. As birds' activities start before or shortly after sunrise, especially during spring and early summer, birdwatchers follow this diurnal pattern. Further, birders are not homogeneous and vary greatly in recreational specialisation. The study was based on an online survey with 2,404 birdwatchers (55% male) who responded to questions about their sleep-wake times and about their birding activities. Birders show the same differences between weekdays and weekends/free days sleep like most other people. However, birdwatching days started earlier than weekdays (14 min) and lasted longer. Thus, birdwatching days are shifted towards an earlier sleep-wake rhythm in total. Birdwatchers experience a sleep curtailment during birding. Instead of sleeping ~30 min longer on weekends, they arise ~15 min earlier, summing up to a sleep reduction of about ~45 min compared to a regular weekend. The more psychologically committed birders are, the less they sleep, the earlier they arise, and the earlier is their midpoint of sleep on birdwatching days; meaning that highly specialised birders shift their sleep-wake rhythm to an earlier time compared to their regular weekend, and even their weekday sleep. Thus, birders may suffer more from the short- and long-term consequences of negative SJL. The results might stand representatively for other nature-related leisure activities.
Keywords: birding specialisation; birdwatching (birding); nature-based recreational activities; social jetlag.
© 2021 The Authors. Journal of Sleep Research published by John Wiley & Sons Ltd on behalf of European Sleep Research Society.